Adjustable circumference scriber



May 2, '1944. T. H. BURCH ADJUSTABLE CIIRGUMFEREVNCE SCRIBER Filed Apr'il 15, 194s 2 sheets-sheet 1.

4 255- @de 4 u /N VEN TQQ May 2, 1944. T. H. BURCH 2,347,659-

ADJUSTABLE GIRGUMFERENCE SCRIBER Filed April 15, 1945 2 Sheets-Sheet 2 /N VEN To 2 Two/w45 H BQQCH Patented May 2, 1944 UNITED STATES ATENT OFFICE (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 1 Claim.

The invention described herein may be manufactured and used by or for Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to scribers, and particularly to a tool for scribing lines at selected distances from a straight or curved edge of the work-piece.

The object of the invention generally is to provide a tool of this character which is more universal in its application than any heretofore known.

More specifically, it is an object of the inventic-n to provide a tool by which circular lines may be inscribed or circumscribed on a workpiece concentric with an existing circular edge of the piece.

Another object is to provide a tool with which one may scribe a line at a given distance from an edge on the work-piece whether said edge is straight or curved.

Other objects and advantages will be perceived as the invention is described in greater detail and reference is made to the drawings, wherein,

Fig, 1 is a top plan View of the assembled scriber.

Fig. 2 is a side elevation of the assembled scriber.

Fig. 3 is an end elevation of the assembled scriber.

Fig. 4 is a transverse section taken at G--Li of Fig. 1.

Figs. 5, 6 and 7 show several applications of the scriber to different situations encountered in practice.

Similar reference characters refer to similar parts throughout the several views.

A base 3, having a body portion IIJ and two oppositely extending arms i2 may preferably be made of heavy sheet stock and offset as at I4, the forward or body portion lil, which is raised by the oiset, being then slotted lengthwise to provide two guides I5 which form a guideway between which the rectangular beam I8 is slidable. Beyond the oiiset I4 the beam lies on the -L top of the base, a yoke 20 being slotted to slidably receive the beam, the yoke being secured to the base over the beam by screws 22. A wing thumb screw 211 is fitted to the yoke for fixing the beam in any position to which it may be adjusted.

At the front end, the beam I8 is drilled for the scriber point 25 which may be adjusted vertically to any desired position and held by tightening the small knurled thumb screw 28.

One or more gauge collars 3! are attached to the underside of each arm I2 of the base 8 by the screws 32. In working from an edge having a large radius, a greater number of the gauge collars SII may be required.

The opera-tion. of the device is illustrated by Figs. 5, 6 and '7. In Fig. 5, a circular line is being inscribed on a work-piece 34, the gauge collars 39 here engaging the outer diameter 36. Two collars Sil are employed on each arm I2 of the base S, since the edge from which the tool is guided has a relatively large radius 38. Due to the odset d in the work-piece, the scriber point 26 is considerably extended.

In Fig. 6, a circular line is being circumscribed on the face 22 of acircular work-piece. Only one gauge collar 3i! on each arm I2 of the base 8 s required because of the small radius 44 on the inside circular edge i5 from which the tool is being guided. The scriber point 26 is extended but slightly.

In Fig. 7, a circular line is being inscribed on a depressed surface 8 within the circular ledge 56 on the work-piece. Two collars 3u are used on each arm I2 of the base 8 because of the relatively large radius 52. The scriber point 25 is here necessarily extended considerably in order that the beam I8 will clear the ledge 5D.

While a single embodiment only of the improved adjustable circumference scriber has been shown and described, other embodiments are contemplated within the scope of the claim, and while several examples of its use have been shown in which circular reference surfaces, bo-th internal and external, are employed, it is obvious that a line may as readily be scribed with reference to a straightor otherwise curved edge on a workpiece.

Having thus described the invention, I claim:

An improvement on an adjustable scriber of the kind having a beam with a scriber near one end, a base with guideways in which said beam is endwise slidable, means to fix said beam against endwise movement in said guideways, arms extending oppositely from said base and gauge means depending from said arms near their ends, said improvement comprising a base which consists of a body portion with two oppositely extending arms at one end, said base being constructed of relatively heavy sheet stock oiiset atwise intermediate its ends, the upwardly offset or body portion being slotted through to provide a sliding guideway for a beam, and each said arm having secured thereto on its underside one or more gauge collars, said beam lying upon the upper surface of the downwardly offset portion, yoke secured tothe upper surface of said downwardly oiiset portion o-ver said beam, said yoke having the underside grooved to slidably receive said beam, and a thumbscrew having threaded bearing in said yoke and adapted to clamp said beam against endwise movement in said yoke.

THOMAS HAROLD BURCH. 

